Up to now, an ejector refrigeration cycle that is a vapor compression refrigeration cycle device having an ejector has been known. Also, as an ejector applied to an ejector refrigeration cycle, for example, Patent Document 1 discloses an ejector that mixes a gas-liquid two-phase ejection refrigerant ejected from a nozzle portion with a drawn refrigerant in the gas-phase state drawn from a refrigerant suction port, and the ejector increases a pressure of a mixture refrigerant of the gas-liquid two-phase state in a diffuser portion (pressurizing portion).
In such a two-phase flow ejector that increases the pressure of the mixture refrigerant in the gas-liquid two-phase state in the diffuser portion, an energy loss such as a wall surface viscosity loss caused by a friction between the mixture refrigerant flowing at a comparatively high speed and a wall surface of the diffuser portion is large. For that reason, an ejector efficiency tends to be lowered. The ejector efficiency means an energy conversion efficiency when converting an energy recovered by the ejector into a pressure energy.
On the other hand, Non Patent Document 1 discloses a liquid ejector that ejects a liquid-phase refrigerant accelerated to a sound speed or higher from an ejection refrigerant passage provided in a nozzle portion, and discloses an ejector refrigeration cycle including the liquid ejector.
In the liquid ejector of Non Patent Document 1, in a gas-liquid mixing portion, an ejection refrigerant of the liquid-phase state which is ejected from the ejection refrigerant passage is mixed with an inflow refrigerant in the gas-phase state introduced from an outside, and a flow rate of a mixture refrigerant of the ejection refrigerant and the inflow refrigerant is reduced to a subsonic speed. With the use of shock waves generated when the mixture refrigerant shifts from a supersonic speed state to a subsonic speed state, the mixture refrigerant is increased in pressure within a relatively short distance, and a gas-phase refrigerant in the mixture refrigerant is condensed.
As a result, in the liquid ejector of Non Patent Document 1, an energy loss such as a wall surface viscosity loss is suppressed to attempt an improvement in an ejector efficiency.